Insulator



Jan. 27, 1931. L H* LEE 1,790,273

INSULATOR Filed Aug. ll, 1928 INVENTOR LeI'I'TnQT, Lee

079m gp his a'orrle 7 Patented Jan. 27, 1931 UNITED STATES PATENT OFFICE y INSULATOR Application led August 11, 1928. vSerialplicn 298,942.

5 odsl of mounting porcelain or glass insulators' on poles, walls, and on various racks for their support. Since the electrical conductor which is supported by the insulator must not come into electrical communication with the 10 object to which the insulator is attached, it

has been found difficult to firmly mount either high or low tension insulators.

Due to the brittle nature of porcelain or glass it has been found impractical to use a 5 threaded male extension integral with and composed of the material of said insulator for the aforesaid purpose of mounting the same. The result is that, heretofore, insulators, particularly those of the class illustrated in the accompanying drawings, havebeen cored out for the fixation of a threaded stem therein. In certain instances the interiors of these cored .out openings have had threads impressed on their walls to receive a male por` tion which serves as the direct mounting means. But, to perfect such a manner of attachment, the cored out portion or hole has to be relatively large to allow the threads therein to be of a size to give sufficient strength. Furthermore, the male portion on which the insulator is screwed must have an outer layer or bushing of soft metal to permit the insulator threads to screw readily on the male portion. That is, the porcelain must contact a soft material or it will stick and cause therupture of the insulator. This has proven a rather impractical and expensive means of mounting insulators. i

Another commonmethod of adapting insulators for mounting has been to center a screw or bolt shank in a cored out region of the insulator, `and then, pour sulphur or lead so called male member in the insulator. It has been found that the torque necessary to mount the screw or bolt of this assembled insulator and screw is brought to bear on the porcelain portion of the insulator, and this therearound to serve asra binder and fix thetorqueloften causes breakage of the insulator before it is suitably mounted.

- A further method of mounting insulators has been to cement or screw an internally threaded .metal bushing into an insulator proper, to permit the insulator to be fixed to any suitable male shank. In all of the'methods outlined there are, necessarily, several pieces carried in stock, and there is considerable woi'k necessary in the eld for the assembly -of the insulator parts or pieces, and for the installation of each insulator. When a screw is permanently fixed in an insulator and screwed into an expansible wall plug, the rain and moisture attack the stem of the screw at the plane of jointure between the wall and the inner surface of the insulator.

The object of the invention is to provide an insulator with a metal core having an internally threaded portion extending from the face of the insulator to afford under certain conditions of installation a more rigid support for electric conductors.

In the accompanying drawings Figure I 1s a view of the insulator, shown partly in 75 vertical section, illustrating a metal V1core secured in the insulator in accordance with my invention; Figure II is a view of an'insulator in which a core of modified structure (an integrally cast core) is secured; and Figure S0 III is a sectional -view through a concrete Wall, illustrating the manner in which the insulator of my invention proves advantageous in use.

The reference numeral l designates the insulator generally, and 2 represents a cored out portion orhole which opens into the base of the insulator. In Figure I there is shown a metal `bushing 3 which is internally threaded at 4. It will be noticed 5 which conforms in size and'shape with the bottom of the recess 2. This similarity in conformation between the bottom of the recess and the inner end of the bushing aids $5 said conformation of the bushing with re- A1100 that this bushing has a shoulder 'or irregular portion Y spect to the recess 2, the said bushing aligns and centers itself in the recess. Molten lead, sulphur, or vother suitable material is then cast into the space between the bushingand the wall of the recess 2. The shoulder 5 serves to prevent the withdrawal of the bushing from the lead. In order that the resulting lead acket or sleeve 6 may be neither rotated nor withdrawn, the innei' Wall of opening 2 'has one or more indentations 7. When the said lead or other suitable binder is cast into the opening 2 and around the bushing 3, it fills the indentations 7, as shown.

Figure Il shows an insulator in which aA suitable metal has been cast to form the entire insulator-mounting core. The shoulder or extension 9 may be formed in the casting operation with the aid of a simple washer like mould, such as that illustrated by the dotted lines 10. This metal core 11 is solid after the pouring, but, obviously, upon drilling and tapping the core l1, as shown, the insulator is in condition for use.

Figure TITv is a sectional View, and shows a hole 12 drilled into a cement wall 13, and a bolt 14 fixed therein by expanding the ductile collar 15. This method of fixing bolts in a hole is well known, and it will not be necessary to describe it in detail. It should benoted that, heretofore, bolts of this type have always extended beyond the plane or surface of the wall in which they were posi'- tioned. This is an undesirable feature, since it often happens that the insulators are reshank. The extension is further advantageous in keeping moisture out of the hole 12 and away from the bolt 14. As the outer diameter of the extension is approximately equal to the inner diameter of the hole 12, it may be seen that the bolt 14 is held rigidly at both ends, and the externalstrain due the supported wire is distributed along the shank of the bolt instead of being concentrated on the member 15. It will be perceived that such distribution of stresses along the bolt would not exist if it were not for an extension, such as the extension 9, projecting into the hole 12. This structure results in a much rmer and stronger mounting than` has been hadin the past. 1t is found that the strength of this arrangement is so great that under a transverse pull (such as that exerted by a suspended electrical conductor) the porcelain will rupture before the bolts may be withdrawn.

The/device is particularly advantageous for use in'tile faced, or stucco covered walls; that is, .it may be screwed on a toggle bolt passing through the walls in the customary manner. The insulator screws up tight against the veneered wall surface and tends to hold the same against the wall rather than tending to pull the veneer away from the wall.

1t should be said that the insulators of the present invention are so simplified that they may be mounted by a simple screwing-on operation, and constitute in themselves'complete articles of manufacture. On the contrary the practice of cementing threaded metal bushings or utilizing expansion sleeves in insulators has required the stocking and handling of Cboth insulators and bushings and/or expansions sleeves. The invention disclosed herein is not limited to relatively reason that the invention is applicable to a support other` than a wall; that is to say, 1 contemplate the use of my invention in mounting insulators on telephone poles, metal insulator brackets, racks, and the like.

What I claim is:

1. 1n combination with an insulator support, which support is provided with a hole and includes a threaded shank fixed to said support concentrically with and inwardly from the mouth of said hole; an insulator comprising a porcelain body having a metal core secured therein, which metal core is internally threaded and extends from the face of said insulator body to nest within the mouth of said hole and receive said threaded shank.

2. The combination of the next preceding claim, in which the metal core in addition to having the above defined structural characteristics comprises a bushing which is first machined and then secured with cast material in the-.insulator body.

In witness whereof, I hereunto set my 

